Turbine nozzle piece parts with hvoc coatings

ABSTRACT

A nozzle for an air cycle machine. The nozzle has a disk section having a central axis. The nozzle also includes a plurality of blades which extend a blade height H from a bladed face of the disk section. The plurality of blades are arranged radially about the disk section. The nozzle has a throat width W defined between each radially adjacent pair of the plurality of turbine blades. The nozzle includes a coating substantially encapsulating the disk section and the plurality of blades, wherein the coating contains more than 91 percent tungsten carbide by volume.

BACKGROUND

The present invention relates to Air Cycle Machines (ACM), such as thetype used in Environmental Control Systems in aircraft. In particular,the present invention relates to novel dimensions and coatings ofturbine nozzles used in ACMs.

ACMs may be used to compress air in a compressor section. The compressedair is discharged to a downstream heat exchanger and further routed to aturbine. The turbine extracts energy from the expanded air to drive thecompressor. The air output from the turbine may be utilized as an airsupply for a vehicle, such as the cabin of an aircraft.

ACMs often have a three-wheel or four-wheel configuration. In athree-wheel ACM, a turbine drives both a compressor and a fan whichrotate on a common shaft. In a four-wheel ACM, two turbine sectionsdrive a compressor and a fan on a common shaft.

Airflow must be directed into the fan section to the compressor section,away from the compressor section towards the heat exchanger, from theheat exchanger to the turbine or turbines, and from the final turbinestage out of the ACM. In at least some of these transfers, it isdesirable to direct air radially with respect to the central axis of theACM. To accomplish this, rotating nozzles may be used to generate radialin-flow and/or out-flow.

Often, it is desirable for components such as nozzles to includecoatings that protect the components from damage. For example, tungstencarbide coatings have been applied using detonation gun coating.

Thermal spraying techniques are known in the art and are often used toapply thick coatings to change surface properties of the component.Examples of known thermal spraying techniques include detonation guncoating, in which high pressure shock waves pass through a gas streamand cause the emission of bursts of the material to be deposited.Another known method of thermal spraying is high velocity oxy fuel(HVOF), in which the fuel combusts continuously, allowing for acontinuous stream of material to be deposited.

SUMMARY

In one embodiment, a nozzle for an air cycle machine is disclosed whichincludes a disk section having a central axis. The nozzle also includesblades which extend from a bladed face of the disk section by a bladeheight H. The blades are arranged radially about the disk section. Athroat width W is defined between each radially adjacent pair of theplurality of turbine blades. A coating substantially encapsulates thedisk section and the plurality of blades, wherein the coating containsmore than 91 percent tungsten carbide by volume.

In another embodiment, a nozzle for an air cycle machine is disclosedwhich also includes a disk section having a central axis. The nozzlealso includes blades which extend from a bladed face of the disk sectionby a blade height H. The blades are arranged radially about the disksection. A throat width W is defined between each radially adjacent pairof the plurality of turbine blades. The coating substantiallyencapsulating the disk section and the plurality of blades has athickness between 50.8 μm and 101.6 μm.

In a third embodiment, a nozzle for an air cycle machine is disclosedwhich also includes a disk section having a central axis. The nozzlealso includes blades which extend from a bladed face of the disk sectionby a blade height H. The blades are arranged radially about the disksection. A throat width W is defined between each radially adjacent pairof the plurality of turbine blades. The coating substantiallyencapsulating the disk section and the plurality of blades comprises ametal alloy having a bond strength greater than 10,000 psi.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a four-wheel Air Cycle Machine.

FIG. 2 is a plan view of a turbine nozzle in the four-wheel Air CycleMachine of FIG. 1.

FIG. 3 is a side view of the turbine nozzle of FIG. 2.

FIG. 4 is a plan view of a portion of the turbine nozzle of FIG. 2,showing the dimensions of the nozzle.

FIG. 5 is a plan view of a turbine nozzle in the four-wheel Air CycleMachine of FIG. 1.

FIG. 6 is a side view of the turbine nozzle of FIG. 5.

FIG. 7 is a plan view of a portion of the turbine nozzle of FIG. 5,showing the dimensions of the nozzle.

FIG. 8 is a cross-sectional view of a three-wheel Air Cycle Machine.

FIG. 9 is a plan view of a turbine nozzle in the three-wheel Air CycleMachine of FIG. 8.

FIG. 10 is a side view of the turbine nozzle of FIG. 9.

FIG. 11 is a plan view of a portion of the turbine nozzle of FIG. 9,showing the dimensions of the nozzle.

FIG. 12 is a plan view of a turbine nozzle in the three-wheel Air CycleMachine of FIG. 8.

FIG. 13 is a side view of the turbine nozzle of FIG. 12.

FIG. 14 is a plan view of a portion of the turbine nozzle of FIG. 12,showing the dimensions of the nozzle.

DETAILED DESCRIPTION

FIG. 1 is a cross-sectional view of Air Cycle Machine (ACM) 2. ACM 2 isa four-wheel ACM, containing fan section 4, compressor section 6, firstturbine section 8, and second turbine section 10, which are allconnected to shaft 12. Shaft 12 rotates about central axis 14.

Fan section 4 includes fan inlet 16 and fan outlet 18. Fan inlet 16 isan opening in ACM 2 that receives working fluid from another source,such as a ram air scoop. Fan outlet 18 allows working fluid to escapefan section 4. Fan blades 20 may be used to draw working fluid into fansection 4.

Compressor section 6 includes compressor inlet 22, compressor outlet 24,compressor nozzle 26, and compressor blades 27. Compressor inlet 22 is aduct defining an aperture through which working fluid to be compressedis received from another source. Compressor outlet 24 allows workingfluid to be routed to other systems after it has been compressed.Compressor nozzle 26 is a nozzle section that rotates through workingfluid in compressor section 6. Compressor nozzle 26 directs workingfluid from compressor inlet 22 to compressor outlet 24 via compressorblades 27. Compressor nozzle 26 is a radial out-flow rotor.

First turbine section 8 includes first stage turbine inlet 28, firststage turbine outlet 30, first stage turbine nozzle 32, and firstturbine blades 33. First stage turbine inlet 28 is a duct defining anaperture through which working fluid passes prior to expansion in firstturbine section 8. First stage turbine outlet 30 is a duct defining anaperture through which working fluid (which has expanded) departs firstturbine section 8. First stage turbine nozzle 32 is a nozzle sectionthat rotates through working fluid in first turbine section 8. Firststage turbine nozzle 32 cooperates with first stage turbine blades 37 toextract energy from working fluid passing therethrough, driving therotation of first turbine section 8 and attached components, includingshaft 12, fan section 4, and compressor section 6. First stage turbinenozzle 32 is a radial in-flow rotor.

Second turbine section 10 includes second stage turbine inlet 34, secondstage turbine outlet 36, second stage turbine nozzle 38, and secondstage turbine blades 39. Second stage turbine inlet 34 is a ductdefining an aperture through which working fluid passes prior toexpansion in second turbine section 10. Second stage turbine outlet 36is a duct defining an aperture through which working fluid (which hasexpanded) departs second turbine section 10. Second stage turbine nozzle38 is a nozzle section that cooperates with second stage turbine blades39 to extract energy from working fluid passing therethrough, drivingthe rotation of second turbine section 10 and attached components,including shaft 12, fan section 4, and compressor section 6. Inparticular, second stage turbine nozzle 38 is a radial out-flow rotor.Working fluid passes from second stage turbine inlet 34 to cavity 35,where it is incident upon second stage turbine nozzle 38. Working fluidthen passes between nozzle blades 50 and 52 (FIGS. 5-7). Turbine nozzle38 is stationary, and the nozzle vanes guide the flow for optimum entryinto the turbine rotor. The flow of causes turbine blades 39 to rotateand turb shaft 12.

Shaft 12 is a rod, such as a titanium tie-rod, used to connect othercomponents of ACM 2. Central axis 14 is an axis with respect to whichother components may be arranged.

Fan section 4 is connected to compressor section 6. In particular, fanoutlet 18 is coupled to compressor inlet 22. Working fluid is drawnthrough fan inlet 16 and discharged through fan outlet 18 by fan blades20. Working fluid from fan outlet 18 is routed to compressor inlet 22for compression in compressor section 6. Similarly, compressor section 6is coupled with first turbine section 8. Working fluid from compressoroutlet 24 is routed to first stage turbine inlet 28.

Similarly, first turbine section 8 is coupled to second turbine section10. Working fluid from first stage turbine outlet 30 is routed to secondstage turbine inlet 34. In this way, working fluid passes through ACM 2:first through fan inlet 16, then fan outlet 18, compressor inlet 22,compressor outlet 24, first stage turbine inlet 28, first stage turbineoutlet 30, second stage turbine inlet 34, and second stage turbineoutlet 38. Additional stages may exist between those shown in FIG. 1.For example, often a heat exchanger (not shown) is located betweencompressor section 6 and first turbine section 8.

Each of fan section 4, compressor section 6, first turbine section 8,and second turbine section 10 are also connected to one another viashaft 12. Shaft 12 runs along central axis 14, and is connected to atleast compressor nozzle 26, first stage turbine nozzle 32, and secondstage turbine nozzle 38. Fan blades 20 may also be connected to shaft12.

When working fluid passes through ACM 2, it is first compressed incompressor section 6, then expanded in first turbine section 8 andsecond turbine section 10. Often, the working fluid is also heated orcooled in a heat exchanger (not shown) through which working fluid isrouted as it passes between compressor section 6 and first turbinesection 8. First turbine section 8 and second turbine section 10 extractenergy from the working fluid, turning shaft 12 about central axis 14.

Working fluid passing through ACM 2 may be conditioned for use in thecentral cabin of a vehicle powered by a gas turbine engine. Bycompressing, heating, and expanding the working fluid, it may beadjusted to a desired temperature, pressure, and/or relative humidity.However, due to the rapid rotation of compressor nozzle 26, first stageturbine nozzle 32, and second stage turbine nozzle 38 with respect tothe working fluid flowpath, these parts need frequent replacement.

FIG. 2 is a plan view of first stage turbine nozzle 32 arranged aboutcentral axis 14. First stage turbine nozzle 32 includes nineteen fullblades 40 arranged along a surface of disk 42. Full blades 40 and disk42 are made of a durable material such as steel, aluminum, or titanium.First stage turbine nozzle 32 is coated with tungsten carbide. Thetungsten carbide coating on first stage turbine nozzle 32 is appliedusing HVOF, allowing for increased hardness and a higher percentage oftungsten carbide as opposed to other materials, such as cobalt. HVOFspraying also results in reduced variability in coating thickness ascompared to traditional coating methods, such as deposition gunspraying.

Disk 42 is radially symmetrical about central axis 14. Full blades 40are spaced equidistantly from one another about the circumferentiallength of disk 42. Each of full blades 40 are also equidistant radiallyfrom central axis 14.

First stage turbine nozzle 32 is a high value component that isrelatively frequently replaced. Damage to first stage turbine nozzle 32may occur due to contact with abrasive particles. Thus, a high strength,durable coating may increase the service life of first stage turbinenozzle 32.

FIG. 3 is a side view of first stage turbine nozzle 32. First stageturbine nozzle 32 contains full blades 40 and disk 42, as described withrespect to FIG. 2.

FIG. 3 illustrates the thickness of first stage turbine nozzle 32. Inparticular, first stage turbine nozzle 32 includes blade height H32.Blade height H32 is the amount of head space between disk 42 and anadjacent component such as a shroud (not shown). Blade height H32 asshown in FIG. 3 is 0.686 cm (0.270 in.). In some embodiments, bladeheight H32 may vary by as much as 0.01 cm (0.005 in.). However, bladeheight H32 of 0.686 cm is ideal for the passage of the desired quantityof working fluid through first turbine section 8 (FIG. 1).

FIG. 4 is an enlarged view of a portion of first stage turbine nozzle32. The portion shown in FIG. 4 shows full blades 40 arranged on disk42.

FIG. 4 illustrates various specific dimensions of first stage turbinenozzle 32. Nozzle passage width W32 is the distance between each fullblade 40 and the radially adjacent full blade 40. In effect, nozzlepassage width W32 is the width of a throat through which working air maybe routed. Nozzle passage width W32 is 0.340 cm. (0.134 in.), but maydeviate by as much as 0.013 cm. (0.005 in.). Flow area A32 is the regionthrough which working fluid may flow. Flow area A32 converges betweenthe vanes until it reaches the throat of first stage turbine nozzle 32,and has a surface area of nozzle height H32×nozzle passage width W32.Due to machining tolerances, flow area A32 area may vary by up to 5%.Flow area A32 is approximately 4.432 square centimeters (0.687 squarein.).

Nozzle passage width W32 is optimized to ensure proper flow and energyextraction from first stage turbine nozzle 32. Increasing or decreasingnozzle passage width W32 would result in too much or too little flowthrough first stage turbine nozzle 32 Likewise, flow area A32 isoptimized to ensure an appropriate quantity of working fluid istransmitted by first stage turbine nozzle 32. A larger flow area A32would result in too much working fluid passing through first stageturbine nozzle 32, while a smaller flow area A32 would result in toolittle.

FIG. 5 is a plan view of second stage turbine nozzle 38 arranged aboutcentral axis 14. Second stage turbine nozzle 38 includes seventeen fullblades 50 and seventeen splitter blades 52 arranged along a surface ofdisk 54. Full blades 50, splitter blades 52, and disk 54 are made of adurable material such as steel, aluminum, or titanium. Second stageturbine nozzle 38 is coated with tungsten carbide. The tungsten carbidecoating on second stage turbine nozzle 38 is applied using High-VelocityOxy-Fuel (HVOF) spraying, allowing for increased hardness and a higherpercentage of tungsten carbide as opposed to other materials, such ascobalt.

Disk 54 is radially symmetrical about central axis 14. Full blades 50and splitter blades 52 are interdigitated and spaced equidistantly fromone another about the circumferential length of disk 54. Thus, fullblades 50 are each located between two adjacent splitter blades 52, andsplitter blades 52 are each located between two adjacent full blades 50.Each of splitter blades 52, and each of full blades 50, are equidistantradially from central axis 14.

Second stage turbine nozzle 38 is a high value component that isrelatively frequently replaced. Damage to second stage turbine nozzle 38may occur due to abrasive particulates in the high velocity airflowdirected by second stage turbine nozzle 38. Thus, a highly durablecoating on second stage turbine nozzle 38 may increase its service life.

HVOF coating of second stage turbine nozzle causes unique physicalcharacteristics that are not possible using traditional coatingtechnologies, such as deposition gun coating. HVOF coating may, forexample, allow for levels of tungsten carbide in excess of 91%. Inaddition, HVOF coating provides for surface hardness in excess of 10,000psi. Furthermore, HVOF coating provides for reduced variability insurface coating thickness as compared to detonation gun coating.

FIG. 6 is a side view of second stage turbine nozzle 38. Second stageturbine nozzle 38 contains full blades 50, splitter blades 52, and disk54, as described with respect to FIG. 5.

FIG. 6 illustrates the thickness of second stage turbine nozzle 38. Inparticular, second stage turbine nozzle 38 includes blade height H38.Blade height H38 is the amount of head space between disk 54 and anadjacent component such as a shroud (not shown). Blade height H38 asshown in FIG. 6 is 0.940 cm (0.370 in). In some embodiments, bladeheight H38 may vary by as much as 0.01 cm (0.005 in). However, bladeheight H38 of 0.940 cm is ideal for the passage of the desired quantityof working fluid through second turbine section 10 (FIG. 1).

FIG. 7 is an enlarged view of a portion of second stage turbine nozzle38. The enlarged portion shown in FIG. 7 shows full blades 50 andsplitter blades 52 arranged on disk 54.

FIG. 7 illustrates various specific dimensions of second stage turbinenozzle 38. Nozzle passage width W38 is the distance between each fullblade 50 and adjacent splitter blade 52. In effect, nozzle passage widthW38 is the width of a throat through which working air may be routed.Nozzle passage width W38 is 0.222 cm (0.0875 in), but may deviate by asmuch as 0.013 cm (0.005 in). Flow area A38 is the region through whichworking fluid may flow. Flow area A38 is the total cross-sectional areaorthogonal to the surface of disk 54 on the bladed side that is notcovered by full blades 50 and splitter blades 52 and through whichworking fluid flows. The portion of flow area A38 identified in FIG. 7is the flow area A between one full blade 50 and one splitter blade 52.In sum, over the entire surface of second stage turbine nozzle 38, flowarea A38 is 7.103 square centimeters (1.101 square inches). Due to minordifferences in machining and/or coating, this value may be as high as7.458 of as low as 6.748 square centimeters.

Nozzle passage width W38 is optimized to ensure proper flow and energyextraction from second stage turbine nozzle 38. Increasing or decreasingnozzle passage width W38 would result in too little or too much flowthrough second stage turbine nozzle 38. Likewise, flow area A38 isoptimized to ensure an appropriate quantity of working fluid istransmitted by second stage turbine nozzle 38. A larger flow area A38would result in too much working fluid passing through second stageturbine nozzle 38, while a smaller flow area A38 would result in toolittle.

FIG. 8 is a cross-sectional view of ACM 100. ACM 100 is a three-wheelACM, containing fan section 102, compressor section 104, and turbinesection 106, all of which are connected to shaft 108. Shaft 108 rotatesabout central axis 110.

Fan section 102 includes fan inlet 112 and fan outlet 114. Fan inlet 112is an opening in ACM 100 that receives working fluid from anothersource, such as a bleed valve in a gas turbine engine (not shown). Fanoutlet 114 allows working fluid to escape fan section 102. Fan blades116 may be used to draw working fluid into fan section 102.

Compressor section 104 includes compressor inlet 118, compressor outlet120, and compressor nozzle 122. Compressor inlet 118 is a duct definingan aperture through which working fluid to be compressed is receivedfrom another source, such as fan section 102. Compressor outlet 120allows working fluid to be routed to other systems once it has beencompressed. Compressor nozzle 122 is a nozzle section that rotatesthrough working fluid in compressor section 104. In particular,compressor nozzle 122 is a radial out-flow rotor.

Turbine section 106 includes turbine inlet 124, turbine outlet 126, andturbine nozzle 128. Turbine inlet 124 is a duct defining an aperturethrough which working fluid passes prior to expansion in turbine section106. Turbine outlet 126 is a duct defining an aperture through whichworking fluid which has expanded departs turbine section 106. Turbinenozzle 128 is a nozzle section that extracts energy from working fluidpassing therethrough, driving the rotation of turbine section 106 andattached components, including shaft 108, fan section 102, andcompressor section 104.

Shaft 108 is a rod, such as a titanium tie-rod, used to connect othercomponents of ACM 100. Central axis 110 is an axis with respect to whichother components may be arranged.

Fan section 102 is connected to compressor section 104. In particular,fan outlet 114 is coupled to compressor inlet 118 such that workingfluid may be transferred from fan outlet 114 to compressor inlet 118.Working fluid is drawn through fan inlet 112 and discharged through fanoutlet 114 by fan blades 116. Working fluid from fan outlet 114 isrouted to compressor inlet 118 for compression in compressor section104.

Similarly, compressor section 104 is coupled with first turbine section106. Working fluid from compressor outlet 120 is routed to turbine inlet124. In this way, working fluid passes through ACM 100: first throughfan inlet 112, then fan outlet 114, compressor inlet 118, compressoroutlet 120, turbine inlet 124, and turbine outlet 126. Additional stagesmay exist between those shown in FIG. 8. For example, often a heatexchanger (not shown) is located between compressor section 104 andturbine section 106.

Each of fan section 102, compressor section 104, and turbine section 106are also connected to one another via shaft 108. Shaft 108 runs alongcentral axis 110, and is connected to at least compressor nozzle 122 andturbine nozzle 128. Fan blades 116 may also be connected to shaft 20.

When working fluid passes through ACM 100, it is first compressed incompressor section 104, then expanded in turbine section 106. Often, theworking fluid is also heated or cooled in a heat exchanger (not shown)through which working fluid is routed as it passes between compressorsection 104 and turbine section 106. Turbine section 106 to extractenergy from the working fluid, turning shaft 20 about central axis 110.

Working fluid passing through ACM 100 may be conditioned for use in thecentral cabin of a vehicle powered by a gas turbine engine. Bycompressing, heating, and expanding the working fluid, it may beadjusted to a desired temperature, pressure, and/or relative humidity.However, due to the rapid rotation of compressor nozzle 122 and turbinenozzle 128 with respect to the working fluid flowpath, these parts needfrequent replacement.

FIG. 9 is a plan view of turbine nozzle 128 arranged about central axis110. Turbine nozzle 128 includes nineteen full blades 130 arranged alonga surface of disk 132. Full blades 130 and disk 132 are made of adurable material such as steel, aluminum, or titanium. Turbine nozzle128 is coated with tungsten carbide. The tungsten carbide coating onfirst stage turbine nozzle 128 is applied using HVOF, allowing forincreased hardness and a higher percentage of tungsten carbide asopposed to other materials, such as cobalt. HVOF spraying also resultsin reduced variability in coating thickness as compared to traditionalcoating methods, such as deposition gun spraying, as will be describedin more detail with respect to FIGS. 15A-15B.

Disk 132 is radially symmetrical about central axis 110. Full blades 130are spaced equidistantly from one another about the circumferentiallength of disk 132. Each of full blades 130 are also equidistantradially from central axis 110.

Turbine nozzle 128 is a high value component that is relativelyfrequently replaced. Damage to turbine nozzle 128 may occur due tocontact with abrasive particles. Thus, a high strength, durable coatingmay increase the service life of turbine nozzle 128.

FIG. 10 is a side view of turbine nozzle 128. Turbine nozzle 128contains full blades 130 and disk 132, as described with respect to FIG.9.

FIG. 10 illustrates the thickness of turbine nozzle 128. In particular,turbine nozzle 128 includes blade height H128. Blade height H128 is theamount of head space between disk 132 and an adjacent component such asa shroud (not shown). In a first embodiment, blade height H128 as shownin FIG. 10 is 0.318 cm (0.125 in). In a second embodiment in which anincreased quantity of working fluid flow is desired, blade height H asshown in FIG. 10 may be 0.393 cm (0.155 in). In some versions of thefirst and second embodiments described above, blade height H128 may varyby as much as 0.01 cm (0.005 in.). However, blade heights H 134 of 0.318cm or 0.393 cm are ideal for ACM 100 (FIG. 8) to pass a desired quantityof working fluid through turbine section 106 (FIG. 8).

FIG. 11 is an enlarged view of a portion of turbine nozzle 128. Theenlarged portion shown in FIG. 11 shows full blades 130 arranged on disk132.

FIG. 11 illustrates various specific dimensions of turbine nozzle 128.Nozzle passage width W128 is the distance between each full blade 130and the radially adjacent full blade 130. In effect, nozzle passagewidth W128 is the width of a throat through which working air may berouted. Nozzle passage width W128 is 0.241 cm (0.095 in.), but maydeviate by as much as 0.013 cm. (0.005 in.). Flow area A128 is theregion through which working fluid may flow. Flow area A128 is the totalsurface area of disk 132 on the bladed side through which working fluidmay flow between full blades 130. The portion of flow area A128identified in FIG. 11 is the flow area A between one full blade 130 andits adjacent full blade 130. In sum, over the entire surface of turbinenozzle 128, flow area A128 is 1.451 cm. squared (0.225 square inches) inthe first embodiment described above, and 1.806 cm. squared (0.255square inches) in the second embodiment described above. Due to minordifferences in machining and/or coating, these values may vary by asmuch as 5%.

Nozzle passage width W128 is optimized to ensure proper flow and energyextraction from turbine nozzle 128. Increasing or decreasing nozzlepassage width W128 would result in either too much or too little fluidflow through nozzle 128A. Likewise, flow area A128 is optimized toensure an appropriate quantity of working fluid is transmitted by firststage turbine nozzle 128. A larger flow area A128 would result in toomuch working fluid passing through turbine nozzle 128, while a smallerflow area A128 would result in too little.

FIG. 12 is a plan view of turbine nozzle 128A, an alternative embodimentcapable of being used in three-wheel ACM 100. Turbine nozzle 128A mayalso be arranged about central axis 110. As with turbine nozzle 128,described above with respect to FIGS. 8-11, turbine nozzle 128A may beused in ACM 100 (FIG. 8). Turbine nozzle 128A includes twenty-three fullblades 130A arranged along a surface of disk 132A. Full blades 130A anddisk 132A are made of a durable material such as steel, aluminum, ortitanium. Turbine nozzle 128A is coated with tungsten carbide. Thetungsten carbide coating on turbine nozzle 128A is applied using HVOFspraying, allowing for increased hardness and a higher percentage oftungsten carbide as opposed to other materials, such as cobalt.

Disk 132A is radially symmetrical about central axis 110. Full blades130A are spaced equidistantly from one another about the circumferentiallength of disk 132A. Thus, full blades 130A are located between twoadjacent full blades 130A, and each of full blades 130A are equidistantradially from central axis 110.

Turbine nozzle 128A is a high value component that is relativelyfrequently replaced. Damage to turbine nozzle 128A may occur due toabrasive particulates in the high velocity airflow directed by turbinenozzle 128A. Thus, a highly durable coating on second stage turbinenozzle 128A may increase its surface life.

FIG. 13 is a side view of turbine nozzle 128A. Turbine nozzle 128Acontains full blades 130A and disk 132A, as described with respect toFIG. 12.

FIG. 13 illustrates the thickness of turbine nozzle 128A. In particular,turbine nozzle 128A includes blade height H128A. Blade height H128A isthe amount of head space between disk 132A and an adjacent componentsuch as a shroud (not shown). Blade height H128A as shown in FIG. 13 is0.305 cm. (0.120 in.). In some embodiments, blade height H128A may varyby as much as 0.01 cm. (0.005 in.). However, blade height H128A of 0.305cm. is ideal for the passage of the desired quantity of working fluidthrough turbine section 106 (FIG. 8).

FIG. 14 is an enlarged view of a portion of turbine nozzle 128A. Theenlarged portion shown in FIG. 14 shows full blades 130A arranged ondisk 132A.

FIG. 14 illustrates various specific dimensions of turbine nozzle 128A.Nozzle passage width W128A is the distance between each full blade 130Aand its adjacent full blade 130A. In effect, nozzle passage width W128Ais the width of a throat through which working fluid may be routed.Nozzle passage width W128A is 0.234 cm. (0.092 in.), but may deviate byas much as 0.013 cm. (0.005 cm.). Flow area A128A is the cross-sectionalarea through which fluid may flow on the bladed side of disk 132Abetween full blades 130A. The portion of flow area A128A identified inFIG. 14 is the flow area A between one full blade 130A and the adjacentfull blade 130A. In sum, over the entire bladed surface side of disk132A in turbine nozzle 128A, flow area A128A is 1.639 square centimeters(0.254 square inches). Due to minor differences in machining and/orcoating, this value may be as high as 1.721 square centimeters or as lowas 1.557 square centimeters.

Nozzle passage width W128A is optimized to ensure proper flow and energyextraction from turbine nozzle 128A. Increasing or decreasing nozzlepassage width W128A would result in either too much or too little fluidflow passing across turbine nozzle 128A. Likewise, flow area A128A isoptimized to ensure an appropriate quantity of working fluid istransmitted by turbine nozzle 128A. A larger flow area A128A wouldresult in too much working fluid passing through turbine nozzle 128A,while a smaller flow area A128A would result in too little.

Each previously described turbine nozzle embodiments is coated. Thecoatings are applied using HVOF. Thus, each previously described turbinenozzle has a base made of any of a range of acceptable base materials,such as steel, aluminum, ceramic, or titanium. A coating is sprayed ontothe base using HVOF, the coating primarily consisting of tungstencarbide. Previously, detonation gun coating was used to apply thecoating.

The coating applied is not pure tungsten carbide. In order to facilitatecoating using detonation gun technology, the coating is often composedof 12% cobalt, plus or minus 2%. Accordingly, the surface coating has anadhesion strength of 8500 psi, plus or minus 5%. However, using HVOF,the coating may have a higher percentage of tungsten carbide. A coatingapplied using HVOF is often composed of 9% cobalt, plus or minus 2%.Often, the coating may contain less than 8% cobalt by volume.Accordingly, the surface coating 164 has an adhesion strength of 10,000psi, plus or minus 5%.

A coating applied using detonation gun technology typically has aminimum thickness of approximately 0.00254 cm. (0.001 in.). These priorart coatings often have a range of approximately 0.00762 cm. (0.003in.), plus or minus 2%. A coating applied using HVOF will typically havea minimum thickness of approximately 0.00508 cm. (0.002 in.), and arange of 0.00508 cm. (0.002 in.).

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof.

Therefore, it is intended that the invention not be limited to theparticular embodiment(s) disclosed, but that the invention will includeall embodiments falling within the scope of the appended claims.

1. A nozzle for an air cycle machine, comprising: a disk section havinga central axis; a plurality of blades which extend a blade height H froma bladed face of the disk section, the plurality of blades arrangedradially about the disk section; a throat width W defined between eachradially adjacent pair of the plurality of turbine blades; and a coatingsubstantially encapsulating the disk section and the plurality ofblades, wherein the coating contains more than 91 percent tungstencarbide by volume.
 2. The nozzle of claim 1, wherein the coatingcontains less than 8 percent cobalt by volume.
 3. The nozzle of claim 1,wherein the plurality of blades consists of 34 blades.
 4. The nozzle ofclaim 1, wherein the blade height H is 0.940 cm.
 5. The nozzle of claim1, wherein the throat width is 0.222 cm.
 6. The nozzle of claim 1, andfurther including a flow area A defined by the surface area along thebladed face of the disk and between the blades, and wherein the flowarea A is equal to 7.103 cm square.
 7. The nozzle of claim 1, whereinthe plurality of blades consists of 19 blades.
 8. The nozzle of claim 1,wherein the blade height H is 0.686 cm.
 9. The nozzle of claim 1,wherein the throat width is 0.340 cm.
 10. The nozzle of claim 1, andfurther including a flow area A defined by the surface area along thebladed face of the disk and between the blades, and wherein the flowarea A is equal to 4.432 cm square.
 11. The nozzle of claim 1, whereinthe blade height H is 0.318 cm.
 12. The nozzle of claim 1, wherein theblade height H is 0.393 cm.
 13. The nozzle of claim 1, wherein thethroat width is 0.241 cm.
 14. The nozzle of claim 1, and furtherincluding a flow area A defined by the surface area along the bladedface of the disk and between the blades, and wherein the flow area A isequal to 1.451 cm square.
 15. The nozzle of claim 1, and furtherincluding a flow area A defined by the surface area along the bladedface of the disk and between the blades, and wherein the flow area A isequal to 1.806 cm square.
 16. The nozzle of claim 1, wherein theplurality of blades consists of 23 blades.
 17. The nozzle of claim 1,wherein the blade height H is 0.305 cm.
 18. The nozzle of claim 1,wherein the throat width is 0.234 cm.
 19. The nozzle of claim 1, andfurther including a flow area A defined by the surface area along thebladed face of the disk and between the blades, and wherein the flowarea A is equal to 1.639 cm square.
 20. The nozzle of claim 1, whereinthe coating has a thickness between 50.8 μm and 101.6 μm.
 21. The nozzleof claim 1, wherein the coating comprises a metal alloy having a surfacecoating adhesion strength greater than 10,000 psi.
 22. The nozzle ofclaim 20, wherein the coating comprises a metal alloy having a surfacecoating adhesion strength greater than 10,000 psi.
 23. A nozzle for anair cycle machine, comprising: a disk section having a central axis; aplurality of blades which extend a blade height H from a bladed face ofthe disk section, the plurality of blades arranged radially about thedisk section; a throat width W defined between each radially adjacentpair of the plurality of turbine blades; and a coating substantiallyencapsulating the disk section and the plurality of blades, wherein thecoating has a thickness between 50.8 μm and 101.6 μm.
 24. The nozzle ofclaim 23, wherein the coating contains less than 8 percent cobalt byvolume.
 25. The nozzle of claim 23, wherein the plurality of bladesconsists of 34 blades.
 26. The nozzle of claim 23, wherein the bladeheight His 0.940 cm.
 27. The nozzle of claim 23, wherein the throatwidth is 0.222 cm.
 28. The nozzle of claim 23, and further including aflow area A defined by the surface area along the bladed face of thedisk and between the blades, and wherein the flow area A is equal to7.103 cm square.
 29. The nozzle of claim 23, wherein the plurality ofblades consists of 19 blades.
 30. The nozzle of claim 23, wherein theblade height H is 0.686 cm.
 31. The nozzle of claim 23, wherein thethroat width is 0.340 cm.
 32. The nozzle of claim 23, and furtherincluding a flow area A defined by the surface area along the bladedface of the disk and between the blades, and wherein the flow area A isequal to 4.432 cm square.
 33. The nozzle of claim 23, wherein the bladeheight H is 0.318 cm.
 34. The nozzle of claim 23, wherein the bladeheight H is 0.393 cm.
 35. The nozzle of claim 23, wherein the throatwidth is 0.241 cm.
 36. The nozzle of claim 23, and further including aflow area A defined by the surface area along the bladed face of thedisk and between the blades, and wherein the flow area A is equal to1.451 cm square.
 37. The nozzle of claim 23, and further including aflow area A defined by the surface area along the bladed face of thedisk and between the blades, and wherein the flow area A is equal to1.806 cm square.
 38. The nozzle of claim 23, wherein the plurality ofblades consists of 23 blades.
 39. The nozzle of claim 23, wherein theblade height H is 0.305 cm.
 40. The nozzle of claim 23, wherein thethroat width is 0.234 cm.
 41. The nozzle of claim 23, and furtherincluding a flow area A defined by the surface area along the bladedface of the disk and between the blades, and wherein the flow area A isequal to 1.639 cm square.
 42. The nozzle of claim 23, wherein thecoating comprises a metal alloy having a surface adhesion strengthgreater than 10,000 psi.
 43. A nozzle for an air cycle machine,comprising: a disk section having a central axis; a plurality of bladeswhich extend a blade height H from a bladed face of the disk section,the plurality of blades arranged radially about the disk section; athroat width W defined between each radially adjacent pair of theplurality of turbine blades; and a coating substantially encapsulatingthe disk section and the plurality of blades, wherein the coatingcomprises a metal alloy having a surface coating adhesion strengthgreater than 10,000 psi.
 44. The nozzle of claim 43, wherein the coatingcontains less than 8 percent cobalt by volume.
 45. The nozzle of claim43, wherein the plurality of blades consists of 34 blades.
 46. Thenozzle of claim 43, wherein the blade height H is 0.940 cm.
 47. Thenozzle of claim 43, wherein the throat width is 0.222 cm.
 48. The nozzleof claim 43, and further including a flow area A defined by the surfacearea along the bladed face of the disk and between the blades, andwherein the flow area A is equal to 7.103 cm square.
 49. The nozzle ofclaim 43, wherein the plurality of blades consists of 19 blades.
 50. Thenozzle of claim 43, wherein the blade height H is 0.686 cm.
 51. Thenozzle of claim 43, wherein the throat width is 0.340 cm.
 52. The nozzleof claim 43, and further including a flow area A defined by the surfacearea along the bladed face of the disk and between the blades, andwherein the flow area A is equal to 4.432 cm square.
 53. The nozzle ofclaim 43, wherein the blade height H is 0.318 cm.
 54. The nozzle ofclaim 43, wherein the blade height H is 0.393 cm.
 55. The nozzle ofclaim 43, wherein the throat width H is 0.241 cm.
 56. The nozzle ofclaim 43, and further including a flow area A defined by the surfacearea of the bladed face of the disk less the area covered by theplurality of blades, and wherein the flow area A is equal to 1.451 cmsquare.
 57. The nozzle of claim 43, and further including a flow area Adefined by the surface area along the bladed face of the disk andbetween the blades, and wherein the flow area A is equal to 1.806 cmsquare.
 58. The nozzle of claim 43, wherein the plurality of bladesconsists of 23 blades.
 59. The nozzle of claim 43, wherein the bladeheight H is 0.305 cm.
 60. The nozzle of claim 43, wherein the throatwidth is 0.234 cm.
 61. The nozzle of claim 43, and further including aflow area A defined by the surface area along the bladed face of thedisk and between the blades, and wherein the flow area A is equal to1.639 cm square.